What's in the little red box on some jump-start leads? (Guess first.)

[@ThumpertTheFascistCottontail]

Many years ago I tried to get into the local nightclub on a saturday night, but the guy on the door wouldn't let me in because I wasn't wearing a tie. So I went back to my car and wrapped my jumper leads around my neck, and tried my luck again. The guy on the door said "o.k, you can come in, but don't start anything"

[@comfortablydoomed6280]

Boooo

[@fraychiken]

Ok that's actually funny. thanks for sharing. :)

[@inductor1.77]

was it dead inside?

[@stefanf922]

Hehe

[@golfman9290]

Pint of electrolyte please.

[@wtfiswiththosehandles]

In case anyone was let down by jumper cables they sell at gas stations and supermarkets (those that have far more insulation than actual copper), here is a recipe for cheap yet indestructible jumper cables: - buy 4 welder ground clamps. Those are very robust and are usually rated for 300A+ - buy 4 lug connectors - buy 6 meters of 25mm^2 welder ground cable (or thicker). You will make two 3m cables out of this, buy more if you need longer. This type of cable is very soft even in low temperatures. - split cable in half, crimp or solder lug connectors onto cable, connect to clamps - congratulations, you have jumper cables that can start a diesel truck.

[@SLAutoRepair]

MasterBata in a pinch you can run smaller wires in parallel with any type of clamp(even hose clamps) to hold the wire on the terminals

[@scootergeorge9576]

@@SLAutoRepair In the days of chrome plated bumpers, two cheap cables in parallel to the positive terminals and the bumpers touching for the ground connection.

[@oliverwatson1567]

My friends managed to jumpstart a car with a couple of the aluminium foil trays you put under barbecues

[@thegeneralissimo470]

I have what is basically a bug-out box. Rechargeable, comes with a light, usb inputs, 12v car jack, standard us power socket, air compressor (although a kinda weak one, works for when your tire either just loses pressure over time, or if you've got a small hole) and the thing weighs about 40 pounds, so it's got the oomph at least, unlike these wimpy starter packs.

[@scootergeorge9576]

@@thegeneralissimo470 - I have one of those too. Also includes a work light. What's your point?

[@toddwest9115]

im guessing its a diode.. to keeps voltagefromgoingback to pack.

[@Noughtta]

possibly for reverse polarity protection

[@divinetruth2875]

What they ^^^ said 👍

[@f-s-r]

@@Noughtta But when connecting the charger with the polarity wrong, it's in series with the battery, so the diode would be forward biased, anyways.

[@alli_moto7154]

is that a joke? 🤦‍♂️

[@MichaelOfRohan]

Zener action?

[@90msg90]

Not only does this protect the li-po (or li-ion) in the power bank against reverse polarity, this also has a significant use in "standard operation". As soon as you fire up your car's engine, the alternator kicks in, delivering around 14V towards battery terminals. Both the alternator and the power bank might not like it (I would expect a significant current going into the li-po), that's why they are so consistent on reminding you in the manual to disconnect the device as soon as the engine starts.

[@johnfrancisdoe1563]

90msg90 Reverse polarity clamping will pass right through those diodes, as the leftover voltage in the car will act like a hugely flat battery drawing a lot of amps until something fails, probably violently. I'll be like shorting a 24V extra beefy battery.

[@blubbspinat9363]

Still, the argument remains valid. Those jump start packs re usually 3S packs, which means they have a maximum voltage of 12.6V when fully charged. High amperage 30-40A at around 14-15V that a car alternator is happy to churn out will make your pack go thermonuclear in a matter of seconds. Diodes prevent that.

[@baxmauer]

90msg90

[@gmodderr]

That happened to me a few years ago, bought a cheap jump start thing on ebay, decided to try it out and intentionally drained my battery Well i hooked it up, turned it on and started the car, worked very well, but my 100A alternator disinigrated the jump starter before i could even exit the car, i guess there was no diodes in that thing lol

[@NoobixCube]

If one wanted to design a LiPo jump start pack with safety foremost in mind, rather than cost, it would be a simple matter to add a voltage sensitive relay to the package, which would detect when the voltage on the car got higher than the voltage in the pack (i.e. when the alternator kicked in). That said, these things are churned out of factories by the tens of thousands in China, and a VSR would add substantial cost to a production run.

[@Talarkas]

When I was like, 11-12 I had a huge interest in electronics and tech, learning what components did, and all that jazz. I have no idea why my interest petered out, but it did. Now this channel shows up and has kinda resparked my interest a bit, while also being very relaxing and entertaining to watch!

[@ryanrichardson5951]

My guess is: “I watch this channel because it’s relaxing but I don’t actually know how electricity works”

[@Songwriter376]

Secret: Neither do the professionals. Tesla did though.

[@ScooterZn]

@@Songwriter376 In what way did he "understand" electricity? I keep hearing this about Tesla but all I get is some confusing conspiracy replies. I'd be grateful if you could explain it.

[@Songwriter376]

@@ScooterZn There are many sources on youtube about him. If you are a reader I suggest the book TESLA, MAN OUT OF TIME as it gives one of the best bios about him. Engineers still do not understand magnetism or how it works but they do know how to use it to generate power. Likewise, they do not understand what electricity is but know how to use it. Tesla, who is the father of most things we use today like electric light, motors etc etc, could understand somehow just exactly how to make an electric motor by understanding the properties of electromagnetic eminations from coils of wire arranged in such a way as to make the motor turn. All wothout notes or drawings. Did it in his mind!!! There are others out there like Stubblefield, Moray etc who made great research and discoveries with explanations as to how a magnetic field really works and how it actually manifests into our dimension but some of those books are tough reads. Don’t pay attention to any crazy theories out there but read a book about his life and discoveries. Many still poo pooh him because he challenged the accepted authorities of his time on how things work. Hope you do investigate and read about this very under rated and genius of a man man who’s discoveries and many inventions shaped the modern world into what it is today. Zoid.

[@stevensmith4449]

Most electricians are bluffers

[@paulbeaumont7485]

Something to do with marbles in a tube and angry pixies in the wall, don’t think you need to know much more than that to be a sparky! Oh, and don’t let the smoke out!

[@drubradley8821]

Maybe the diode pack is there to protect the lithium battery pack from the alternator's output voltage once the engine starts?

[@mronlyone9114]

Yeah that makes sense it was that simple

[@stephenbates8370]

Yeah I thought the same thing to be fair 👍

[@EFLO3D]

Geeze thanks for spoiling it!

[@trojanhorse5363]

But the alternator charge controler limits the output voltage 🤔

[@robertheinkel6225]

If the clamps are used incorrectly, connections reversed, the jumper will not work.

[@RalphV]

Hey Clive, i just wanted to say thank you for making these excellent videos. I've learned a lot i wouldn't have otherwise, and been entertained the whole way. I recently got an electronics kit for my birthday and i'm having s great time experimenting with it, as well as trying some soldering tricks i've learned from you. Thank you

[@TehMG]

In this case, the diodes are used to prevent the alternator from shoving tons of current into the lithium battery when the vehicle starts, nothing more. It does NOT provide reverse polarity protection. If you hook the booster pack up backwards, things will get quite exciting quite quickly, guaranteed, unless the jump pack has some sort of protection internally. I've had bad luck with these lithium jump start packs. For one thing, their performance drops dramatically when cold, which ironically is also when you're most likely to need it. I much prefer ultracapacitors for jump starting. You get WAY more amps and they are not affected by low temperatures nearly as much.

[@rich1051414]

Yep, these cables can't help with reverse hookups. It will cause the positive terminal to look like -12v to the charger, so it will dump everything it can into the battery attempting to reverse charge it. That would go very very bad. It needs some brains to detect a negative voltage scenario, letting it know the cables are backwards. That's actually easy to implement... but don't expect the feature!

[@wingerrrrrrrrr]

I have two ultracap jump packs, mainly cause I think they're so cool, and also because they don't have a limited lifespan like the lithium packs do. Although ask me again in 10 years to see if the ultracaps are still ultra.

[@petermcarthur7450]

I bought one of these jump starters recently and, like Clive, the first thing I did was open that little red box to see what was inside. And I’m extremely glad I bought it! I left my lights on overnight, and was greeted by a flat battery in the morning. The jump starter didn’t work on the first try, so I left it to recharge the car’s battery for 10 minutes and then I was good to go!

[@andreasdill4329]

Use your power supply and put a load of 5A over the diode-module. Then measure the voltage-drop, this will give you a more useful measurement.

[@trisymphony]

3:40 what a beautiful soldering job

[@teeter_1253]

ikr XD

[@jhughes8160]

Yeah, that's what I thought!

[@alanowa123]

At this point it's more like welding

[@xtdycxtfuv9353]

could of just poured liquid solder at this point

[@yessiryousir]

Pretty good for 6 year old children i thought lol

[@pizzablender]

For a dummy load, run a number of car headlight bulbs in parallel. You can even switch them in one by one to see what happens (and avoid most of the current spike caused by cold filaments).

[@billysgeo]

Those jump starters are simply 3S lipos batteries (and b-grade noname ones at that). I made one just using a battery I already had for my quadcopter (4000mah 40C), some heavy gauge wire and some good quality clamps. The only problem with them is that when the car turns over and starts you must I immediately disconnect the LiPo from the car as the voltage from the alternator (>14V sometimes) can damage the LiPo. And that's why they now put diodes in series with them.

[@MrWilliamtomkinson]

As a seller of lithium jump packs, I can tell you so many are crap. there are some good quality units such as the NOCO, but anything that uses this cable are rubbish, the clamps break at the hinges, the cables melt in the connector and at the teeth as all the current travels in through 1 side, also most of the cables are aluminium. the diodes serve 2 purposes, firstly they stop reverse connection, for about 5 seconds until they explode. they also stop the pack from being reversed charged from the alternator, as there are only 3 Li-Po pouches inside the 14v from the alternator is to high. the other problem is after cranking for a few seconds the diodes fail. now all these failures are assuming the li-po pouches dont explode first. most of the packs that use these leads wont start more than a 4 cylinder. or charge a phone. i should do a teardown, i have several different types of packs sitting around.

[@Thanatos4655]

Good i have a 4cyl

[@fredlast4547]

I have a 3 cylinder.

[@Sunny01331]

I've got one of these clips that started to melt that box covering the diodes when starting an old truck with a carburetor, meaning it took awhile, but it never failed! This explains the heat! And we need to see a vid on how much amps these things can take, push it to the max! Love your vids by the way

[@spikeydapikey1483]

Not a bad price for the clips alone either.

[@bigclivedotcom]

It is probably worth buying for the clips.

[@cojones8518]

could probably use the diodes for a solar charger, that was a pretty good FV.

[@Muonium1]

totally. my nipples are hard in anticipation just looking at them!

[@Aubreykun]

Depending on how soft the jaws are they could be quite useful beyond anything electrical as well. They look a lot more robust than the standard chinese plastic spring clamps that are found all over.

[@MV60]

Would make an excellent set of charge leads. Already has what looks like an ec5 on the end, and those clamps are better than the tiny alligator clips that come with a typical hobby battery charger. I use mine to top up my car battery, an imax b6ac. It has a setting for the lead acid battery and outputs only up to 5A, the lead would handle it fine. BTW, I knew it would contain a diode in that box before the vid started. :) Really, what else would it be?

[@petersack5074]

3:40 those are schottky barrier rectifiers (SBL2040CT= 250 amps max) SBL2045 = up to 150 amps. both 40-45 peak reverse volts, to protect alternator.

[@Bostish2]

damn, I always thought it was just one of those massive car fuses.

[@sausagedog52]

for anybody wondering, its not for reverse polarity protection, its because the full charge voltage of the pack inside is 12.6v, thats fine for starting the car but once it does start the alternator brings the battery voltage up to 14.4.or even as high as 14.7, if this was reverse fed into the lithium pack it would destroy the cells, likely in an explosive manner.

[@playdav485]

i believe the block in the wire is a lossless diode made of mosfets to prevent the car from charging the jump starter

[@badenpobjoy1877]

Your very last sentence "for me" covered 99% of what l was trying to learn in this video... no doubt about you techinical (electrical) expertise though......cheers baden

[@markmatt9174]

Just finished watching Project Farm videos on the jump starters shootout. Great info from Him without any bs

[@goldwinger5434]

I looked at those lithium jumper packs for over a year before I bought one. I read some reviews, crunched the numbers and then took the plunge. I bought a brand called "Bully," more on that later. I charged mine and threw it into the back of my car. Not a month later my Volvo V70 had a dead battery. Out came the jumper pack. The car has the battery in the back and a terminal under the hood for "jump starts." That terminal has never done me any good even with another car supplying power. So I hooked the Bully to the batter, positive to positive and negative to negative. Turned the key and it started fine. Recharged the battery and put it back in the car. Checked it a few months later and the battery was swelling. Oh, oh. Called Bully and I had a new one in a few days. Last week, I had a dead battery again. Bully to the rescue. So far, I'm a believer. Just buy a brand name at a reputable store.

[@waltp3373]

The 'magic' red box seems straightforward to me. You basically have 8 diodes in parallel to handle the large current draw and prevent reverse polarity hookup and voltage back flow from the 13v-14v alternator when the car starts. The low voltage drop is due to there being 8 diodes in parallel where each silicon diode would drop around .7V. I don't see any confusion about this setup. Also, you mentioned that it could draw 400 amps. I'm sure those (10 ga.?) wires would melt at 400 amps. Put a clamp meter on it to see what it's really drawing when you start the car. I may do my own such test as soon as I get a DC clamp meter.

[@grlpeterson]

Yeah, Clive, PLEASE blow up your car in video for us all! Please?

[@WhatTheHellIsWrongWithYouu]

The low gauge wire can support 400 amps for a short period of time like jump starting requires.

[@worddunlap]

2000 Amps DC on 10 AWG stranded wire , copper plated AC/CU plated. 400 Amps would fry it to a crackling crunch. It may hold before bursting into flames but someone would get the shit burned out of them. I'd like to see it at 2000 amps or even 1000. Yes they are relying on it being a short period. New car starters are tiny compared to ones from the 1970s. That said I have a jump starter pack with a lead acid battery, made by a major company that has worked spectacularly for years. FYI made by Schumacher but only claims 650 amps. It starts my tractor, my truck and the wife's Toyota Camry. It has saved us lots of time. hassle and money...The original cost was about 50 dollars. I will be changing the battery in it this year.

[@TristanJCumpole]

I'm sure that the spark gap between the two diode rails is Electroboom-level testworthy!

[@danwic]

*Arcing intensifies*

[@TristanJCumpole]

@@danwic Excelsior!

[@thoughtguardian]

I’m just getting into understanding electronics and even though most of these videos go over my head they are always enjoyable! Even if it’s just to get vocabulary down, I think they help me learn. Thanks!!

[@liamwiltshire3400]

Is it a little elf on a hamster wheel to generate enough energy to jumpstart the batter?

[@queazeproductions]

Liam Wiltshire guessing after watching the video isn't fair

[@tyttuut]

Of course not, don't be ridiculous. It's obviously a gnome in there.

[@davey2k12]

Behave it's like a hamster turning the London eye lmfao

[@the486kgman2]

The Tyttuutface if you connect it to a step up transformer connection to a battery

[@scootergeorge9576]

@@the486kgman2 Transformer, more that meets the eye. Transformer, little elf on a hamster wheel...

[@gummel82]

The boss of who's manufacturing these should be told to hold these while his "1000A" clamps are at the test. He should show us how it's done and i'd like to see his frying face when he's holding them

[@mikeselectricstuff]

That's a fairly typical drop for a big schottky at low currents, it doesn't stay that low under load though.

[@bigclivedotcom]

I'd guess it might go quite high at the real life starting currents. Oh, remember your little pyrophoric incident? I've just had one that I also caught on video.

[@kjrchannel1480]

Something many people don't know is. If you connect more than one diode in parallel the effective threshold voltage drop will be lowered. Just like resistance is lowered in a parallel circuit.

[@robozstarrr8930]

.. matching diode characteristics in parallel (Voltage forward (drop) or current sharing ) is "better" if the diodes are matched (one technique is to get match diodes where their breakdown voltage is within 50mV @ some I ).... if not the Vf (shared) won't be the lowest.

[@energycrafts8206]

A lot of people think the diodes are for reverse voltage protection when putting the cable clamps to the battery backward. The diodes do not offer reverse voltage protection as noted further. If you connect in reverse then first the battery and booster are in series and will be dead shorted across each other the degree depending on the battery state of existing charge. (The high current surge might be enough to cause a diode failure if it failed opened. This would be a quasi fuse protection effect, but not reliable as diodes can fail as shorts as well.) The boost back will try to discharge and recharge the car battery in reverse voltage polarity as the voltage at the boost pack is greater than the car battery. A very harmful effect to lead acid batteries. If it could still crank the engine, then the alternator output voltage if greater than the boost pack would try to reverse charge it. Very bad, but might tolerate a momentary connection. But the alternator would attempt charging the car battery. In normal operation. The diodes serve simply 2 purposes of isolation: Prevent the car battery and/or alternator from trying to charge the boost pack since the factory likely has there own preferred charging profile and a cc/cv type charger.

[@activemanishere]

So in theory you could delete this feature? I have been through 3 sets of these leads because they keep desoldering themselves when jumping a car. If i deleted and kept the time attached to the car at a minimum it wouldn't actually hurt the box right?

[@Kris_M]

No, in case the LiPo is 3 cells in series it can handle 12,6V max. Once the car starts and the generator is putting out 13-14V, it would destroy the LiPo pack, possibly in a very violent manner. The diodes prevent this.

[@nomennudum4592]

In other words it is for reverse polarity protection, but connecting the car battery backwards *isn't* reversing polarity - it's the desired polarity but with an extra current source.

[@Poop-nu1so]

@@nomennudum4592 well two batteries in series increases the voltage, and so normally the amperage can increase as a result, but that's irrelevant here because the two batteries have virtually no load between each other. It's a dead short. Don't think there will be any (usable) voltage left for the vehicle during that situation. You may even present some nice reverse polarity voltage available to the vehicle's system. If that ends up flowing through the system get ready to pop a few components. Don't worry it can only cost hundreds or one thousand dollars to fix.

[@billmaghan]

@@activemanishere I got rid of my diodes and it works great. I keep the time attached to the car minimum.

[@KogiSyl]

Actually, schottky (and normal) diodes increase forward voltage drop with current, so on multimeter it can show 0.1V, but in operation, during jump starting the current be around 400-600A. That would be 60-85A per diode (there are 8 diodes), and the voltage drop would be above 1.1V (the datasheet shows 1.1V drop at 40A instantaneous current and then the chart ends :P ). At this range of current - schottky and normal diodes behave quite similarily, there wouldn't be noticeable differences in heat generated by schottky and normal diodes in this application. For a drop of 1.1V at 85A - each of the 8 diodes would generate 93.5W of heat per diode (750W for all 8 diodes). Possibly much more, because the chart doesn't show forward drop at such high currents. Also, I think the datasheet I saw shows voltage/current chart per package (two diodes) not per diode - that would mean that the heat will be even higher :P. I would say, that after fairly short usage this plastic little box would melt away, far sooner than any isolation on the cables. You may consider it a fuse of sorts :P. A kind of fuse that leaves your hands burned if you use the jump starter too much :P.

[@milksheihk]

Even before lithium jump packs there were some supposedly "EFI Safe" jumper leads had a similar box on them, supposedly because ordinary jumper leads would fry the electrical systems of EFI cars, but everyone just uses ordinary leads on EFI cars & nobody has fried one.

[@tyttuut]

Wouldn't be long until those cars stopped working thanks to Y2K though. I hope they had their Y2K-compliant jumper cables ready.

[@AmaNotaGogo]

I have one of these jump starter things and must say that it works. The first two tries are not successful to start the car but the third time it starts the motor sunning as the lithium cells are now hot. Very happy with the result.

[@Rich77UK]

Stupid question...The numbers on each of the diodes is different. Does that mean they are differently rated? I dont suspect its just a different manufacturers number as they dont tend to do this...confused mechanical brain here.

[@khronscave]

The top rows are some datecodes or fab-codes or something; the part numbers are on the bottom row. I see two SBL2040CT and two SBL2045CT - the only difference between those is the reverse voltage rating (40v vs 45v), but that shouldn't affect anything in practice, in this usage scenario.

[@Mixbag]

cant find those diodes on ebay for cheap. is there an alternative diode that could be used ? was thinking in making a board of 5 of these to add to my car charger for reverse polarity protection ?

[@superdau]

The changing number quite likely are datecodes when they were produced. With the numbers all over the place it tells you they used "leftovers" and not new stock from a reel (the dates also look like the parts are from 2001/2002). In a proper design you would never do that, because you must not put diodes in parallel without precautions (this is true for LEDs as well). Diodes from different batches will have slightly different characteristics even if it's the same part number. And mixing different part numbers like they did (2040CT and 2045CT) is a big nono as well. The problem is, if the diode aren't almost exactly the same (not just the type, but in measured electrical characteristics) and thermally coupled to each other (at least they are on the same piece of board, so that's a bonus), there's always one that conducts slightly more current than the others at the same voltage. More current means more heat for that diode and diodes conduct better when they are hotter! So the diode takes even more current, heating up more and more. Depending on how much you overload it, it might die immediately or after repeated use. Now that that diode is dead, it's time for the second best conducting to take it's turn, except now the current will be devided between on less diode, so more current for all of them and die even faster. That's also a good way to kill LEDs if you skimp on limiting the current of each strand of LEDs individually.

[@khronscave]

+Mix Bag, here's a link to options available from Mouser (Schottky diodes, 20A and above, 40v and above, sorted by price). www.mouser.co.uk/Semiconductors/Discrete-Semiconductors/Diodes-Rectifiers/Schottky-Diodes-Rectifiers/_/N-ax1mj?Rl=ax1mjZgjdhqdZ1yuoc7iZ1ypakakSGTax1mjZgjdhq5Z1yuoc6sZ1ypakalS1ya6ncwZ1yuo4zqGT&Ns=Pricing%7C0

[@superdau]

+Mix Bag Check how the diodes are oriented. These diodes are not reverse polarity protection (no point in having that with power sources on both ends anyway). They are back feed protection.

[@PerspectiveEngineer]

You've made the last six months a joy. Making the boring intriguing. Clive! You devil...

[@radry100]

No magic smoke? I'm disappointed

[@bigclivedotcom]

There will be lots of unexpected smoke and flames in the next video.

[@samgaus]

Not unexpected anymore :(

[@superhands290]

Clive did you get a new microphone?

[@MrKnowwun]

I shall be very upset now if there isn't.

[@dos541]

connect the lead across a big battery 800+ cca and then there will be magic smoke

[@ACELog]

Good info, Clive! Never thought of the issue of higher Alternator voltage (as others are mentioning) needing to be blocked from the jump pack.

[@jonathanseeley7988]

I'm guessing wire straight through! (That would be hilarious) EDIT: I was wrong, but hey, Clive suggested it as well :D

[@DieDoeDa]

@bigclivedotcom: there seem to be four different (according to the printing on them) kinds of diodes in the red thingy, you only looked at one of them when reading the type around 3:35+... strange.

[@fightfairfightfair]

This is a Big Clive video, so I'm just going to shout things like "Bridge Rectifier". Even though a Bridge Rectifier wouldn't be in a cable designed for DC.

[@rambo1152]

Feeding DC into a bridge rectifier is a handy technique to make the device operate normally on AC or DC irrespective of the polarity. Eg. anything electronic that is connected to a telephone line will use this technique.

[@ZXRulezzz]

FULL BRIDGE RECTIFIER

[@DigGil3]

There's enough diodes for one, tho.

[@TheDessonator]

no it would be a capacitive dropper

[@bashkillswitch]

Irony: ends up being filled with half bridges...

[@scootergem]

If you connect your jump starter to a battery that is fully charged and your jump starter didn't get recharged after you used it last then current would flow from the highly charged battery to the depleted one. In the case of a lithium battery that might mean it would get more amps than it could handle without damage. Another scenario might be where you drain your jump start battery and just as that happens the car starts and throws power back to the jump start battery faster than it could take it. MHO

[@zacandmillie]

Fascinating video, very well explained. If only I knew what the hell it all meant!

[@jasonjamrs7413]

It's a start of a rabbit hole he goes deeper and deeper he explains it clearly enough but you still need the understanding of it all

[@espensund1996]

😂

[@morantaylor]

I guessed it! The diode will prevent the Alternator killing the LiPo when the car starts. A care with a 120A alternator would kill the LiPo very quickly with the surge current.

[@seanet1310]

fuse is too obvious so I am going with half added diode attempt to stop the car charging the battery or reverse polarity protection (but being from China the diode will be grossly under rated. )

[@seanet1310]

MMM. that was actually reasonably decent spec. not bad.

[@wogfun]

I've had tremendous success with a lithium powered jump start pack. First, I jumped my neighbor's minivan that previously failed to start using a standard size jump pack. Then, my mechanic saw the mini lithium in my car and asked if he could try it out on a vehicle he had stuck on his lot for some time. His professional full-size packs all failed to start this car. The look on his face when my tiny lithium pack jumped this vehicle was priceless. He immediately asked for the Amazon link and bought himself one.

[@topcopy98]

You can always count on Big Clive to tackle the big mysteries of life.

[@unheard128]

The newer leads on these packs have a relay inside them that automatically cuts out so you may want to take a look at one of those.

[@bami2]

small thermonuclear fusion reactor

[@kalleklp7291]

Nah...the box would have to be yellow then.

[@ACommenterOnYouTube]

It stops the alternator's reverse current (charging current) from hitting the battery pack. That is why they advise you to remove it immediately after start.

[@Lumibear.]

A device to prevent reversing the polarity of the neutron flow!

[@user-lr7nm7hd1d]

I didnt realize i was watching a UK video narrated by Robin Williams lol. Keep up the good work. Yall have a similar voice

[@simoncrabb]

I guessed diode! What's the prize?

[@NeuronalAxon]

A balloon full of Magic Smoke.

[@onradioactivewaves]

But was it an np or a pn junction?

[@whitcwa]

Clive, for your test load, consider a bank of car headlights with switches for each between two bus bars. Ten bulbs with 20 switches for high/low beam filaments will give you 1000 A capability. I doubt you'll need more than that. Or you could use a coil of wire in a barrel (or large sink) of water. We used to test 5V/200A power supplies that way.

[@davidg954]

try using a salt water load, tub of salt water and one of the electrodes v, (arrow) shaped move up and down to allow adjustment of load,

[@andrewwhite1793]

spodula the Vampire Yes I saw that method used to control the speed of a Big Wheel at a fun fair years ago.

[@inventor1v]

I have a Yaber Yr 500 jump starter and it's a brilliant bit of kit. It has already started my van several times with a totally flat battery! Thankfully the parasitic draw is now fixed.

[@MicraHakkinen]

4:58 Hey Clive, as you probably have realized by now, the reason for the very low Vf you're measuring is because each diode has a Vf of 0.6V (as you'd expect and as confirmed by the datasheet), however what you're measuring is 8 of them in parallel.

[@neil1058]

Are...Bart. just think about what you said! They are not resistors so you don't divide the voltage by the number of diodes old chap.

[@knutruben1]

I know this is a old video, but i have one of these that i fried trying to start my car. It is constructed in the same way, but the tin is a low meltpoint metal like rose metal making it effectivly work as a fuse. What happend to mine was that the main lead melted and fell of. The diodes are probably there in case of someone reversing polarity on the terminals.

[@DreStyle]

fuse,,cant,think about something else

[@DreStyle]

dammit. I saw one with capacitors ...want to buy....but the price ..damn 380 euros

[@sciencetestsubject]

they indeed act as quasi fuses, however the main reason for these diodes is so after the car starts, the car's alternator doesn't cram 40-50A into the liPO pack.

[@putrid.p]

Erik Bruijn and ui

[@DreStyle]

mondayfool Yeahhh ...if I didn't answer so quick I could have known however tose with caps don't have them you can charge them via the leads in seconds

[@erg0centric]

start booster? wouldn't it be easier to service your car battery once every five years?

[@Sirruthford]

so glad this video showed up in my feed as my bank leads shat themselves and replacing the diode was just becoming too common. im so glad I now know the name of the part and wea to find it. thanks for the info

[@xcruell]

Well i guessed "a diode" so im right and wrong all together? :D

[@FireAndGasoline]

I've seen a few of these fail, the wires desolder themselves and the plastic box melts. From continued cranking like you thought.

[@jlucasound]

Wouldn't the diodes protect "things" in the event someone inadvertently connects the leads backwards?

[@KentuckyRanger]

@ 3:40 WOW! They really over protected! I was expecting maybe 2 high current diodes, but 8? WOW! Cudos to this company!!!

[@rochr4]

„What"s in the box miss fox” - love Ya! ;)

[@kieranhall1998]

I have an Aukey jump starter that I had a peek inside the cables. Unlike many of the Chinese ones I was pleasantly surprised to find both cables going into a slightly larger box which had the negative feeding straight through with a fuse but the positive went through all kinds of safety and support circuitry. It had the flowback resistance from diodes, a relay to switch the output from powerbank on or off depending on the voltage of the car battery it was attached too and a couple thermal cutouts also. Very impressed compared to this Chinese cable, but for so cheap you can't expect much more than a few diodes!

[@MexieMex]

I guessed correctly, perhaps I am learning something from watching all these electronics videos after all LOL

[@alandaters8547]

Also note the cheap plastic jaws. Both contacts are metal, but with no jumper between each side of the jaw, only one is actually making contact. On regular jumper cables I have taken off the metal pieces, installed a heavy jumper wire to connect them, and then used small bolts to reattach the contacts to the plastic. (Metal frame jaws should have at least some current carrying ability through the jaw frames.)

[@backyardbasher]

Reverse Polarity protection incase an idiot like tries using them.

[@Panda3style]

Thats what i thought backyardbasher, diodes are ment for one way. Eden's Aquaponics why is polarity protection impossible?

[@superdau]

There's no point of reverse polarity protection when there is power sources on both ends. It is backfeed protection.

[@ronme68]

Yes this is how most reverse polarity protection is implemented. I think Dave Jones did a video on this.

[@ronme68]

And what happens when you are jumping a battery and connect it up wrong? You know connecting the the red to negative - and the black to positive +. This is also called reverse polarity, it is also called a dead short. These diodes are a one way check valve type of device for electricity keeps idiots from burning out the electric systems in the car.

[@superdau]

Take a look again. The way the diodes are mounted they *conduct* from car the battery when the cable is connected with the wrong polarity. Guess why? Because it's not a reverse polarity protection.

[@alanb76]

The Lipo batteries in jump starters have large surface area internally and can deliver surprising amounts of current. Most starters only need a couple hundred amps, and these batteries can deliver that for a few seconds. As mentioned before, their 3 cell design produces less voltage than the running alternator and the low resistance of the battery would draw too much current which is not good for the battery or the car's alternator, so diodes make sense. Note that many car starting packs have more sophisticated boxes in their cables that do look for reverse polarity and protect against more faults, they won't start the car unless they see some voltage there, so a truly dead battery will not trigger them. These units contain FETs so they can control the current. Good luck with your research! Carbon pile loads for car batteries would be a good tool for your investigation, or a large collection of parallel FETs on a big heatsink to make a load bank with some analog controls.

[@mattmacd2009]

I love watching your videos, almost as much as do pretending to understand what in hell you're saying!!

[@janetgray2184]

I am pretending i understand that.

[@WhiteDieselShed]

I think you have just found the ideal solution to connecting several 12v batteries to a small bank of solar panels but where each battery can power its own circuit and not another circuit from another battery. I think i explained that properly? eg. 4x 12v batteries . 100w panel connected to all 4 through these cables. Then each battery connects to an LED lamp. Thanks

[@papinkelman7695]

4 schotty diods solderd to a braslike connector.... just guessing

[@jack8407]

sure....

[@erikjohansson1814]

I'm guessing diodes inside, most likely SBL2040CT. Im quite sure it must be four of those in parallel soldered direct onto two individual brass plates.

[@Sudz3]

Guess: Diode.

[@Sudz3]

DING DING DING! booya! I figured it'd be to protect cheap lithium booster packs from polarity issues

[@johnmcclain3887]

Always good no violence necessary to open the plastic. I always find these interesting, seeing how they manipulate electronics to get their desired outcome. Thanks!

[@legion2k988]

What's in the BOX!!!??? any SE7EN fans? lol

[@SMOBY44]

Hey Big Clive. I believe the diodes (which was my guess for the contents of the box) would be to prevent battery fires and the like from attaching the leads in reverse polarity. Nothing like connecting two batteries to each other in series!

[@FinlayDaG33k]

There's a hot girl in there :D can't think about something else :D

[@thelosteights9012]

My first guess is a fuse, but I'm gonna guess capacitor because maybe it can help with starting?

[@gary851]

my guess - magnet? to reduce noise?

[@tigerchills2079]

you mean like a ferrite choke, eh? Not magnets but ferrimagnetics.

[@gary851]

ye exactly , im not electrician but u know what i meant.

[@TheEulerID]

There is a bit of a misunderstanding about what is happening with these sort of jump leads and use with battery packs. It is not the case that significant amounts of current flow through the lead when the vehicle is started, what actually happens is that the battery pack dumps energy into the car battery, and hopefully enough to give it enough charge to start the car. It doesn't require the delivery of thousands or even hundreds of amps from the lithium batter packs. I've even seen versions that plug into cigarette lighter sockets (albeit deliver more than 15A that way and it could well blow a fuse). Even full size vehicle-to-vehicle jump leads require something like that with some partial charging of the "recipient car's" battery. The jump lead will help quite a bit in that case, but unless it's a very thick one, it's going to need some assistance from the battery in the car being started.

[@ryanmacewen511]

Could a 2V difference of Car (alternator running at 14.5V) actually hurt the booster pack? Assumning it's 12.5V nominal? I ask because I've had 2 sets of these jumper pack leads have the positive wire desolder itself from the diode board in use. 2nd one was done for me by my brother. I'm wondering if I can bypass the board altogether. I have a DB Power jumper pack which does work OK, but the leads like to fail. I use it for other lower current applications as a 12V source (testing lights, or printer control boards), without any protections.

[@uN1Qu3DZ]

These diodes are very common in cheap ATX PC power supplies, they are used on 3.3v and 5v output rails.

[@Electronzap]

I was wondering what was in that box lol. My 10A leaded schottky diodes get down to about 0.1 forward voltage while being diode measured but when passing a little bit larger current through it, I think it quickly went to 0.25V, if not more. I wish it was more stable lol. I had to scrap some circuit ideas I had because I planned on a closer V difference as current went up when I was waiting for them to arrive.

[@karebu2]

I've used 3 different jumpstarters successfully before. They are all brandless and from china. I'm really interested in how they work. Thanks in advance

[@EricWillis77]

I have seen 10awg wire carry 100 amps dc current briefly but the insulation will heat up and fall off with immense amounts of smoke and the wire will get red hot in the middle and burn into! So thinking these jumpers are going to crank out 1000 amps or more is very optimistic LOL. GREAT VIDEO AS ALWAYS 🤠

[@branonmack]

Doesn't your resistance decrease with every diode you put in parallel? This would explain the extremely low resistance.

[@gazzahuck9766]

The diodes in parallel allows them to share the current (10 amps max each = total 80 amps ) wether in parallel or not, each have a forward voltage drop (which is what he was measuring) of 0.6 volts. This is not a resistance measurement but the voltage drop across the PN junction of the diode. I would not expect having them in parallel would show a reduced parallel junction voltage drop of under 0.2 volts like he measured as the drop is inherent in the design of diodes and placing them in parallel I would expect the parallel Vfwd to remain the same. Note. It wasn’t resistance that he was measuring. . But having measured many diodes in my career I have never paralleled them..

[@boastyy]

Just a quick question. I have a couple of these leads, I had them given to me and was going to put the clamps on my car battery charger. It's a standard car mains charger not a lithium quick starter that came with small clips which are hard to fit onto the battery terminals. Would using these leads with the diode box be unsafe for use with this charger or should I just use the clips and cut off the box. You mentioned the possibility of the box heating up and that the lithium pack chargers are not left on the car for long. So I am thinking if a standard charger might be left on over night there might be a problem. Thanks mate.

[@nerys71]

Decent quality versions of this (complete sets) are quite effective! even a small 800a unit was able to start my small block v8 2002 dodge dakota naked (no battery just the jumper) I was quite impressed. No magic smoke The good one will only run so long to prevent you burning them up or worse setting off the lithium pack :-) I only buy ones that charge via USB since the other ones inevitable become paper weights when you use the damned dedicated charger cord :-) ones with usb charger ports are the best. lithium batteries degrade from lack of use. so being able to use it as a usb power bank means you can exercise the battery a little between times you need to use it which keeps them healthy longer. I can't wait till they release some LIFEPO4 versions. those should have a much much longer lifespan.

[@cutiepiecatloveallanimals6602]

It’s a cigarette lighter, older cables sometimes have that, the ones with the fold out ashtray on the negative side are very rare.

[@TheDevilVaper]

I'm guessing a fuse or some sort of protection thingymabob. (written when the ad was playing)

[@SuperAWaC]

i didn't even know what these leads were for, i had to actually look up lithium jump starters to see pictures of what the leads actually go with, and since they are lithium, and these are being attached to a car with an alternator, probably some kind of lithium bomb mitigation device

[@seannot-telling9806]

Clive what would you get if you used that module in a full wave bridge rectifier?

[@bigclivedotcom]

You'd need four to make a full wave bridge rectifier. At the moment it's a half wave rectifier.

[@seannot-telling9806]

@@bigclivedotcom I should of been a bit more clear on that. 4 of the modules so that you would have a full wave. That would give you 12 total diode pairs or one red box per side. Sorry about that.

[@sidewinder15599]

I have one of these kits. Mine is rated for max current of 400A. And it will only let you try to start for 3-5 seconds before it times out, so you can't just hold the key on and continue to draw. And it really has been enough to start my work F-150 on multiple occasions.

[@hommie789]

Diode for reverse protection in cans you hook them up to a battery backwards. Should have lights also but not always, usually will have a red and green LED to show when they hooked up correctly or reverse polarity.

[@tin2001]

Same design as mine. Except the datasheet for the rectifier packs in mine say 20A, and they blobbed on the solder much more uniformly and right up to the wire. I've never started anything with mine... Originally bought it to start our mower, but have only used it to test trailer lights so far. I did try to start a mower with it, but I think the mower has a dud starter relay. I'm curious whether it would be safe to wire one of these up permanently on a small engine like a ride-on mower.... Do those diodes prevent any sadness?

[@CalcProgrammer1]

My guess was correct! The only other thing I could think of than the things you said was diode, for reverse polarity protection.